Process of preparing maleic and succinic acid from furfural by electrolysis



' Patented Apr. 16, 1929.'

I'OFFICE. A

TEIJIRO .YABUTA, OF SETAGAYA-MACHI, EBABA-GORI, JAPAN, ASSIGNOR TO Z AIDAN H OJIN RIKAGAKU KENKYUJ'O,

' PROCESS OI PREPARING HALEIC AND S'U'COINIC ELECTROLYSIS.

1T0 Drawing. Application filed larch 31,1926,

This invention relates to. the of maleic and succinic acid from furfural by electrolysis and the ob'ect of the invention is to preparethese acids y far better efliciency 5 than any other process hitherto known.

-In carrying out my invention, furfural dissolvedor suspended'in an acid or a salt solution, is oxidized by electrolysis. Maleic and succinic acid may be isolated from the resulting oxidation product which consists of their mixture.

Moreover, b usin the proper materials for the electro es an also by employing the proper current density, either Ihaleic or suceinic acid can be obtained as the main product.

Maleic acid can fumaric acid by the usual methods. By the reduction of maleic as well as fumaric acid,

succinic acid can also be produced.

Example 1.

A two-compartment cell, the compartments being separated from each other by a porous diaphragm is employed. The anodic compartment contains 5 per cent sulphuric acid 'inwhich 'furfural is dissolved or suspended, whilst the cathodic compartment contains 10 per cent sulphuric acid. The electrodes are advantageously made of lead pipe coils which serve also as cooling means by passingwatcr through them. A relatively low current density, for example,"say,0.02 amps. per sq. cm. is employed and the temperature kept at C.- The electrolysis is "continued, until the anolyte no longer gives the characteristic reaction of furfural with aniline acetate, and

it is then moderately concentrated. On cool- 1 ing mixed crystals. of succinic and maleic acid (80 per cent and 20 per cent respectively) separate. a They are collected an isolated from each preparation easily be converted into other by fractional crystallization.

01 'roxyo, JAPAN.

ACID FROM FUBFURAL BY Serial No.98,917, and in-Iapan June 22, 1825.

Some more crystals are obtained from the mother hquor on further evaporization, but

If succinic-acid alone is desired, the current is reversed in the same apparatus after the furfural is perfectly oxidized. The maleic acid mixed with converted into succinic acid. The cathodic solution is moderately concentrated and cooled. The crystals of succinic acid which separate are collected and purified by recrystallization from hot water.

Example 52.-

The electrolysis is carried out as in the Example 1, except a lead peroxide anode is used instead of-a lead one, and a relatively high current density, peres per sq. cm. 1s employed. In this case, chiefly maleic acid is produced and theyield reaches 7 5 per cent'of the theory.

It is advantageous to use the anodic solution obtained in this case for the preparation of fumaric acid. For this purpose, an amount of sodium chloride corresponding to the sulphuric acid contained in th added and boiled for about half an hour. On cooling, the fuma-ric acid converted from maleic acid by the catalytic action of hydrochloric acid, crystallizes out. It is collected and recrystallized from hot water.

In these operations described above, increased-yield is obtained by the addition of vanadium, cerium or manganese compounds as catalysis in the anolyte.

I claim: y

The process of preparing maleic and succinic acids which comprises electrolyzing an acid solution of furfural.

In testimony whereof I aflix TEIJIRO my signature. YABUTA.

succinic acid, is reduced and for example, say, 0.06 ame solution, is 

